a Prius’s “gears” are entirely artificial. nevermind the fact that its “gear” selector is an affront to humanity.
There is nothing “artificial” about the Prius transmission. It has the same planetary configuration you would find in a typical automatic, they just run the load against a generator. Quite an elegant design, really, though the selector is not very aesthetically pleasing to me. The really annoying thing is that you have to hold your foot on the brake at a stoplight, even if the engine is totally silent.
He’s referring to the fact that the Prius transmission does not have discrete gear ratios between the engine and the wheels. “Downshifting” a Prius is not the same as downshifting a Honda CRV; any apparent ratio of engine RPM and wheel speed is an artifact of how fast the driveline control computer chooses to spin the generator.
Doesn’t really have the same configuration. IIRC the Prius transmission uses only a single planetary gearset, vs. multiple gearsets in a modern AT. In addition, the Prius has two inputs (engine+motor) and one output (or, if you’re coasting or decelerating, two outputs and one input); a regular AT has only one input and one output.
Same here. 30 Northern Wisconsin winters.
I also drove my MILs Prius recently and it was the worst winter car I have ever driven.
A story from my past:
Many years ago, my family was on a driving vacation in a 1963 Chevy II Nova. The automatic had two forward gears.
One day on this vacation we drove up a place called Hat Peak in eastern Oregon, from the top of which we could see three states (Idaho, Washington and Oregon).
Then we had to drive down. A narrow, winding, steep road. Soon the brakes started glazing over. With only two gears, the lower gear wasn’t very low and it didn’t slow us down very well. We all spent a very nervous (hour? 30 minutes?) while my father managed to get us down in one piece (kudos to him).
So that is at least one occasion where I wished that our automatic had a truly low gear that would have slowed us down to 5mph or so.
Roddy
I was asleep while my wife drove us from Yosemite back towards San Francisco along the Tioga Pass Road. Her screaming woke me up at the bottom because the car was smoking furiously and we had no brakes at all as we approached the intersection to highway 395 at the bottom.
Dropping 3,000 feet in elevation for 60 miles did not advise her to alter her approach to braking. If I hadn’t talked her down and gotten her to gradually drop to 2 and then L, we would’ve drifted directly into the crossing highway lanes. (Finally stopping resulted in the car’s passengers smoking furiously).
I don’t know why it helps to be in a lower gear when you get in a rut, but it certainly does. But the other advantage of having the low gears in the snow is it keeps your car from going faster than 2nd gear, which can be handy if you need to go down a long, windy, snow covered hill like the one 1/4th a mile from my house.
This is quite contrary to my experience. When I need to crawl out of a sticky situation, it usually helps if I can shift to 2nd to limit wheel spin. I have a manual, and in snowy situations, starting in 2nd is preferable to 1st. I’ve also spent the first half of my driving years with an auto, and, at least in mine, starting in 2 had no advantage over D in such a situation.
You musta taken the long way around? Tioga Pass is on the east side of the park, and SanFran is on the west side.
In any event, yes, Tioga Pass is an excellent example of a road where the ability to hold the transmission in a lower gear makes for a pleasant journey on the way up (it eliminates repetitive upshifting/downshifting), and a survivable one on the way down (it eliminates running off the road due to fried brakes).
Good answer.
Another answer is, if they could seamlessly integrate engine, transmission, and brakes, then we wouldn’t need L and 1, because engine braking would be used by default, and disc brakes would only kick in when the engine isn’t enough.
That’s what a Prius does. They did a nifty job of it, but braking still feels a bit odd until you get used to it, and the response isn’t nearly as even as with a typical car with good brakes.
The point is, on a typical car, the engine/transmission system can see demand to accelerate and infer load, but it doesn’t see demand to slow down. The main reason is simplicity. The added complexity to avoid needing 1 & 2 wouldn’t be justified by any market share increase. In fact, most people would hate it. The Prius justifies it because braking charges the battery. Without this benefit it wouldn’t be worthwhile.
See above.
Evidently you’ve never driven a rear-wheel-drive car. I haven’t yet driven my wife’s Prius in snow but I wouldn’t expect any serious problems. I’d expect it to be no worse than my minivan (I’ve been driving minivans since about 1987, in Michigan until 2000.)
When taking that road my wife ignored my advice to use engine braking – not sure why, she’s usually pretty reasonable. Fortunately, it didn’t cause any obvious harm to her sister’s Jeep.
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When I lived in Pittsburgh, lower gears came in handy when driving snow-covered hills. When descending, they kept the brakes from overheating, and breaking on snow-covered hills always carries the risk of sliding.
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Engine braking on slippery roads is usually a bad idea, as most cars these days have adaptive braking (pulsing the brakes when traction is lost) but no adaptive engine braking. It would be a good idea on a car with really crappy brakes that bite too easily, and without adaptive braking. But if you’d engine brake those same hills on dry pavement, then you probably should on snow too.
Yeah, mixed that up. We weren’t heading directly home, but camping our way there indirectly. I should’ve been more clear.
We are on the second generation of drivers that as a group have never driven with drum brakes. Their parents may not have driven on drums either.
When everyone drove drums everyone downshifted on hills. If they didn’t they would lose their brakes due to overheating.
Now due to disc brakes and their greater fade resistance people don’t realize what can happen.
Remember the old truck driving rule. Never do down a hill in a higher gear than you used to climb it.
On the north road out of Sequoia NP, there are signs warning you to downshift. It is a very snaky road and very steep, I was darn glad to have 2 & 1 on my Focus AT.
I drove nothing but rear wheel drive cars for the first 10 years I had a license.
I once drove a (manual transmission) Isuzu Trooper down Old Priest Grade Road. Even with the transmission in 2nd gear, I still had almost no brakes at the bottom - I had to use both feet on the brake pedal to stop at the end of the road.
Eh? Most people not born with a silver spoon in their mouths will have driven a car with drums (at least at the rear) at some point. I’ve had two and I’m 30.
Heck, there’s new cars that still come with rear drums. But I assume he means cars with front drums which are a whole other experience.
I have a dumb question.
What’s the procedure for downshifting a regular automatic? I’ve only owned standard transmissions or 4WD vehicles since I started driving. If I was in a regular automatic, and needed to downshift for a steep hill, do I just do it? Stop first? Shift to neutral and let off the gas, then shift down? There’s no clutch. I feel like I’m missing a step.
Just move the stick. The car will take care of the rest.